U.S. patent number 4,901,103 [Application Number 07/201,905] was granted by the patent office on 1990-02-13 for image recording apparatus using pressure sensitive sheet.
This patent grant is currently assigned to Brother Kogyo Kabushiki Kaisha. Invention is credited to Kiyoharu Hayakawa, Yumio Matsumoto, Akira Sago, Osamu Tagaki, Masashi Ueda.
United States Patent |
4,901,103 |
Hayakawa , et al. |
February 13, 1990 |
Image recording apparatus using pressure sensitive sheet
Abstract
A pressure developing device having a pair of pressure
developing rollers in an image recording apparatus. A
pressure-sensitive recording sheet can be fed to pass between the
pressure developing rollers, and has a pressure-sensitive image
bearing layer on one surface thereof. A developer sheet can
selectively be fed to pass between the pressure developing rollers
in superposed relation to the pressure-sensitive image bearing
layer. The pressure developing rollers are spaced from each other
by a gap which is greater than the thickness of the
pressure-sensitive sheet and smaller than the combined thickness of
the pressure-sensitive sheet and the developer sheet. The pressure
developing device also includes a friction roller held against a
surface of the pressure-sensitive recording sheet opposite to the
image bearing layer and rotatable for frictionally feeding the
pressure-sensitive recording sheet.
Inventors: |
Hayakawa; Kiyoharu (Ama,
JP), Matsumoto; Yumio (Kasugai, JP), Ueda;
Masashi (Nagoya, JP), Sago; Akira (Nagoya,
JP), Tagaki; Osamu (Nagoya, JP) |
Assignee: |
Brother Kogyo Kabushiki Kaisha
(Aichi, JP)
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Family
ID: |
26474517 |
Appl.
No.: |
07/201,905 |
Filed: |
June 3, 1988 |
Foreign Application Priority Data
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Jun 8, 1987 [JP] |
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62-142554 |
Jun 8, 1987 [JP] |
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62-142555 |
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Current U.S.
Class: |
355/406;
100/158R; 100/171 |
Current CPC
Class: |
G03B
27/32 (20130101); G03F 7/0027 (20130101); G03B
2227/325 (20130101) |
Current International
Class: |
G03B
27/32 (20060101); G03F 7/00 (20060101); G03B
027/52 () |
Field of
Search: |
;355/27,28
;100/156,158R,160,168,169,171,176 |
References Cited
[Referenced By]
U.S. Patent Documents
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4727392 |
February 1988 |
Stone et al. |
4806982 |
February 1989 |
Yamamoto et al. |
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Primary Examiner: Hix; L. T.
Assistant Examiner: Rutledge; D.
Attorney, Agent or Firm: Oliff & Berridge
Claims
What is claimed is:
1. A pressure developing device for use in an image recording
apparatus which uses a pressure-sensitive recording sheet and a
developer sheet, comprising;
a pair of pressure developing rollers, said pressure-sensitive
recording sheet being fed to pass between said pressure developing
rollers and having a pressure-sensitive image bearing layer on one
surface thereof, said developer sheet being selectively fed to pass
between said pressure developing rollers in superposed relation to
said pressure-sensitive image bearing layer, said pressure
developing rollers being spaced from each other by a gap which is
greater than a thickness of said pressure-sensitive sheet and
smaller than a combined thickness of said pressure-sensitive sheet
and said developer sheet.
2. The pressure developing device as defined in claim 1, wherein at
least one of said pressure developing rollers is movable toward and
away from the other pressure developing roller.
3. The pressure developing device as defined in claim 2, further
comprising:
a pair of backup rollers disposed behind and held against said
pressure developing rollers, respectively;
a load lever supporting said one of the pressure developing
rollers, said load lever having a pivotally supported end and an
adjustably positioned opposite end which is resiliently urged to
displace said one pressure developing roller toward the other
pressure developing roller.
4. The pressure developing device as defined in claim 1, further
comprising a friction roller held against a surface of said
pressure-sensitive recording sheet opposite to said image bearing
layer, said friction roller being rotatable at a constant speed for
frictionally feeding said pressure-sensitive recording sheet.
5. A sheet feed mechanism for feeding a web-like pressure-sensitive
recording sheet for use in an image recording apparatus which
comprises an exposure unit, and a pressure developing unit disposed
at a downstream side of said exposure unit, said pressure-sensitive
recording sheet being selectively superposed with a developer sheet
at said pressure developing unit, said sheet feed mechanism
comprising;
a supply roll for supplying said pressure-sensitive recording
sheet, said pressure-sensitive recording sheet having a
pressure-sensitive image bearing layer on one surface thereof and
being fed to pass between said pressure developing unit, and said
developer sheet being selectively fed to pass between said pressure
developing unit in superposed relation to said pressure-sensitive
image bearing layer;
a takeup roll for winding said pressure sensitive recording sheet;
and,
a friction roller held against a surface of said pressure sensitive
recording sheet opposite to said image bearing surface and
rotatable at a constant speed for frictionally feeding said
recording sheet.
6. The sheet feed mechanism as defined in claim 5, wherein said
friction roller is positioned at a downstream side of said pressure
developing unit and upstream of said takeup roll.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an image recording apparatus using
a pressure sensitive sheet. More particularly, the invention
relates to a pressure developing device in the image recording
apparatus for developing a latent image on a pressure-sensitive
recording sheet and transferring the image as a visible image onto
a developer sheet, under pressure. The invention also relates to a
sheet feeding mechanism for feeding a web like pressure sensitive
recording sheet for use in the image recording apparatus.
U.S. Pat. No. 4,440,846 discloses an image recording system in
which a developer sheet and a photosensitive pressure-sensitive
recording sheet exposed to light bearing a latent image are
superposed on each other and pressed together to develop the image
on the developer sheet. The photosensitive pressure-sensitive
recording sheet has a coated layer of pressure-rupturable
microcapsules encapsulating a photosensitive composition. Such
image forming technique is generally referred to as transfer type
image recording method in which the developer material is coated on
a substrate such as a developer sheet, which developer material is
reacted with encapsulated chromogenic material provided on a
separate sheet as described in U.S. Pat. No. 4,399,209.
Generally, the photosensitive pressure-sensitive recording sheet is
in the form of a roll, and the developer sheet is in the form of a
cut sheet. The photosensitive pressure-sensitive recording sheet is
normally gripped or nipped between a pair of pressure developing
means or rollers. When microcapsules on the photosensitive
pressure-sensitive recording sheet are ruptured by being pressed
between the pressure developing rollers, the photosensitive
composition is released from the ruptured microcapsules. One
problem with the conventional arrangement is that the released
photosensitive composition tends to be attached to the surfaces of
the pressure developing rollers.
In another aspect, the photosensitive pressure-sensitive recording
sheet is fed by either a takeup roll which pulls the recording
sheet or a pair of feed rollers which grip and feed the opposite
side edges of the web like recording sheet. Feeding the
photosensitive pressure-sensitive recording sheet with the takeup
roll is disadvantageous in that as the photosensitive
pressure-sensitive recording sheet is wound on the takeup roll, the
diameter of the takeup roll is progressively increased and the
speed at which the recording sheet is fed is progressively
increased so far as the takeup roll is rotated at constant angular
velocity. As a result, the latent image on the photosensitive
pressure-sensitive recording sheet, which latent image is formed by
the light-exposure to an original, may be distorted or the exposed
area on the photosensitive pressure-sensitive recording sheet may
be brought out of exact registry with the developer sheet, to
thereby degrade the resultant final visible image on the developer
sheet.
It would be possible to control the speed at which the recording
sheet is wound on the takeup roll in accordance with the diameter
of the takeup roll. However, this would require a sensor for
detecting the speed of travel of the photosensitive
pressure-sensitive recording sheet as well as a highly accurate
speed-controllable motor for driving the takeup roll, resulting in
an increased cost of manufacture.
On the other hand, where the feed rollers are used to grip the side
edges of the photosensitive pressure-sensitive recording sheet, the
side edges of the recording sheet are not available for image
recording since the microcapsules on the side edges are ruptured by
the feed rollers. Therefore, the use of the feed rollers has an
economic disadvantage in that the photosensitive pressure-sensitive
recording sheet must have an increased width so as to provide
sufficient zones undergoing such feeding only, and also suffers a
maintenance problem in that any photosensitive composition
deposited on the feed rollers must be cleaned away.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pressure
developing device having pressure developing rollers which do not
exert a pressure on a photosensitive pressure-sensitive recording
sheet when no image should be developed.
Another object of the present invention is to provide a pressure
developing device which comprises pressure developing rollers that
are positioned so that the torque required to be produced by a
drive motor for rotating the pressure developing rollers in
gripping a photosensitive pressure-sensitive recording sheet and a
developer sheet is reduced, thereby lessening the load on the motor
or reducing the size of the motor.
Still another object of the present invention is to provide a sheet
feed mechanism having a simple structure which is capable of
feeding a photosensitive pressure-sensitive recording sheet at a
constant speed.
According to the present invention, there is provided a pressure
developing device comprising a pair of pressure developing rollers.
A gap defined between the rollers is optimumly provided, which is
one of the features of this invention. A pressure-sensitive
recording sheet is fed to pass between the pressure developing
rollers, and has a pressure-sensitive image bearing layer on one
surface thereof. A developer sheet is selectively fed to pass
between the pressure developing rollers in superposed relation to
the pressure-sensitive image bearing layer. The pressure developing
rollers are spaced from each other by the gap which is greater than
the thickness of the pressure-sensitive sheet and smaller than the
combined thickness of the pressure-sensitive sheet and the
developer sheet.
The pressure developing device also includes a friction roller held
against a surface of the pressure-sensitive recording sheet
opposite to the image bearing layer and rotatable at a constant
speed for frictionally feeding the pressure-sensitive recording
sheet.
According to the present invention, there is also provided a sheet
feed mechanism in the image recording apparatus for feeding an
elongated recording sheet having an image bearing surface and
unreeled from a supply roll, the sheet feed mechanism comprising a
friction roller held against a surface of the recording sheet
opposite to the image bearing surface and rotatable for
frictionally feeding the recording sheet.
The above and other objects, features and advantages of the present
invention will become more apparent from the following description
when taken in conjunction with the accompanying drawings in which a
preferred embodiment of the present invention is shown by way of
illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings;
FIG. 1 is a schematic vertical cross-sectional view showing an
image output apparatus incorporating a pressure developing device
according to the present invention;
FIG. 2 is an enlarged vertical cross-sectional view showing the
pressure developing device shown in FIG. 1; and
FIG. 3 is a schematic cross-sectional view showing the pressure
developing device, with a sheet feed mechanism combined
therewith.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 2 schematically shows an image output apparatus including a
pressure developing device 12 having a pair of pressure developing
rollers 1, 2 disposed in confronting relation to each other. The
apparatus also includes a pair of backup rollers 3, 4 positioned
behind and held against the pressure developing rollers 1, 2,
respectively. As shown in FIG. 1, a photosensitive
pressure-sensitive sheet 15 coated on one side with a layer of
pressure-rupturable microcapsules is unreeled from a supply roll 13
stored in a roll sheet cassette 14 and is passed through an
exposure unit 17 disposed between two horizontally spaced guide
rollers 16a, 16b. Then, the photosensitive pressure-sensitive sheet
15 runs between the pressure developing rollers 1, 2 and around a
separator roller 18, and is wound on a takeup roll 19.
An original 20 to be imaged or copied is set in the exposure unit
17, which includes a light source 21 such as a fluorescent lamp
that is horizontally movably disposed beneath the original 20. A
developer sheet cassette 23 is positioned downwardly of the
pressure developing device 12, and houses a supply of cut developer
sheets 23 therein.
As shown in FIG. 2, the backup roller 3 held against the pressure
developing roller 1 has a roller shaft 5 rotatably supported by a
load lever 7 having one end pivotally mounted on a pivot shaft 8
and the other end on which a load adjusting rod or screw 10 and a
load spring 9 are mounted. The load adjusting rod 10 has a threaded
end threaded through a block 10a attached to the casing of the
pressure developing device 12. The load lever 7 is normally urged
to swing toward the pressure developing roller 1 by the biasing
force of the load spring 9. The swinging movement of the load lever
7 is limited by a load stopper screw 11 threaded through the block
10a because of the abutment between the distal end of the screw 11
and the load lever 7. Therefore, the gap or spacing between the
pressure developing rollers 1, 2 can be adjusted by adjustably
turning the load stopper screw 11 in the block 10a. According to
the present invention, the gap between the pressure developing
rollers 1, 2 is selected so as to be larger than the thickness of
the photosensitive pressure-sensitive recording sheet 15, but
smaller than the combined thickness of the recording sheet 15 and
the developer sheet 22.
The image output device operates as follows: First, the original 20
to be imaged is inserted into the exposure unit 17. The fluorescent
lamp 2 is horizontally moved back and forth to apply light which is
transmitted through the original 20 to the photosensitive
pressure-sensitive recording sheet 15 which is thus exposed to the
light in the pattern of an image on the original 20. Then, the
photosensitive pressure-sensitive recording sheet 15 is fed to the
left (as shown) into overlapping relation to a developer sheet 22
supplied from the developer sheet cassette 23. At this time, the
gap between the pressure developing rollers 1, 2 is smaller than
the combined thickness of the recording sheet 15 and the developer
sheet 22. Therefore, the gripping force or pressure applied by the
pressure developing rollers 1, 2 is applied to the sheets 15, 22 to
form a developed image on the developer sheet 22 in the manner
described in Japanese Laid-Open Patent Publication No. 58-88740.
More specifically, the pressure developing rollers 1, 2 press the
sheets 15, 22 to rupture those microcapsules on the sheet 22 which
are not photo-cured in the exposure unit 17, for thereby releasing
the dye precursor that reacts with the color developers on the
sheet 22 to develop an image on the sheet 12. At this time, the
load lever 7 is slightly spaced from the load stopper screw 11
because of the sheets 15, 22 sandwiched between the pressure
developing rollers 1, 2, so that the resilient force of the load
spring 9 is applied to the pressure developing roller 1 for
effective image development under pressure.
After the development, the photosensitive pressure-sensitive
recording sheet 15 is separated from an output image sheet 24,
which is the developer sheet 22 with the developed image thereon,
by the separator roller 18, and is then wound on the takeup roll
19. After the developer sheet 22 has moved beyond the pressure
developing rollers 1, 2, the pressure developing rollers 1, 2 do
not apply any pressure onto the photosensitive pressure-sensitive
recording sheet 15, since the gap between the pressure developing
rollers 1, 2 is larger than the thickness of the recording sheet
15. Therefore, the microcapsules on the recording sheet 15 are not
ruptured by the pressure developing rollers 1, 2, and hence the
photosensitive material contained in the microcapsules is not
subjected to pressure by the pressure developing rollers 1, 2.
The pressure developing rollers 1, 2 are therefore not smeared by
the photosensitive material contained in the microcapsules. Thus,
the pressure developing rollers 1, 2 can be used for a long period
of time without frequent maintenance or overhauling. Further, since
the gap is provided between the pressure developing rollers 1, 2,
which gap is slightly larger than the thickness of the
photosensitive pressure-sensitive recording sheet 15, the torque
required to rotate the pressure developing rollers 1, 2 when the
developer sheet 22 is also gripped between these rollers 1, 2 is
reduced. Therefore, the drive source, e.g., a motor, for rotating
the pressure developing rollers 1, 2 is subjected to a smaller
load, may be of a smaller size, and consumes a smaller amount of
energy.
FIG. 3 shows a pressure developing device 12' which is
substantially the same as the pressure developing device 12,
wherein like parts and components are designated by the same
reference numerals and characters as those shown in FIGS. 1 and 2.
The pressure developing device 12' includes a sheet feed mechanism
according to the present invention. The sheet feed mechanism
comprises a friction roller 25 disposed above the pressure
developing device 12'. The friction roller 25 is positioned such
that the photosensitive pressure-sensitive recording sheet 15
travels around the friction roller 25 while the back surface of the
recording sheet 15, opposite to the coated side thereof, is being
held against the friction roller 25, and is directed toward the
takeup roll 19. The friction roller 25 comprises a rubber roller
having a high coefficient of friction for exerting high frictional
resistance to the recording sheet 15. The friction roller 25 is
operatively coupled to a drive source (not shown) so as to be
rotated at a constant speed.
During operation of the image output apparatus, when no developer
sheet is supplied between the pressure developing rollers 1, 2, the
photosensitive pressure-sensitive recording sheet 15 is pulled by
the frictional forces produced by the friction roll 25 and fed
between the pressure developing rollers 1, 2. When a developer
sheet 22 is superposed on the recording sheet 15 and these sheets
22, 15 are pressed by the pressure developing rollers 1, 2 for
image development, the speed of travel of the sheets 22, 15 is
controlled by the gripping forces applied by the pressure
developing rollers 1, 2, rather than by the frictional forces
applied by the friction roller 25. Therefore, before and after the
developer sheet 22 are nipped by the pressure developing rollers 1,
2, the photosensitive pressure-sensitive recording sheet 15 is
tensioned by the friction roller 25 without being slackened, and is
fed at a constant speed by the friction roller 25 regardless of the
diameter of the takeup roll 19. Since the photosensitive
pressure-sensitive sheet 15 is fed along at a constant speed, as
described above, the developer sheet 22 can be brought into exact
registry with the recording sheet 15, so that a desired image can
be developed and recorded to a nicety. Moreover, inasmuch as the
friction roller 25 is simple, it is manufactured at a low cost.
The takeup roll 19 is rotated with a torque and at a speed which
are large enough to wind the photosensitive pressure-sensitive
recording sheet 15 which has been pulled by the friction roller
25.
The pressure developing device 12, 12' may be associated with a
thermal fixing device for thermally fixing the image on a developer
sheet 22 discharged from the pressure developing device. The light
source 21 may be a tungsten lamp. While the photosensitive
pressure-sensitive recording sheet 15 is shown as exposed to light
that has passed through the original 20 held against the recording
sheet 15, the recording sheet 15 may be exposed to light which has
been reflected from the original 20 and focused on the recording
sheet 15, or light which has passed through the original 20 and
focused on the recording sheet 15.
Although a certain preferred embodiment has been shown and
described, it should be understood that many changes and
modifications may be made therein without departing from the scope
of the appended claims.
* * * * *